Current regulator



Dec. 21, 1965 Filed June 5, 1962 1 EL L United States Patent 3,225,292 CURRENT REGULATOR Taken Miura, Tokyo-to, Japan, assignor to Kabushiki Kaisha Hitachi Seisakusho, Tokyo-to, Japan, a jointstock company of Japan Filed June 5, 1962, Ser. No. 200,246 Claims priority, application Japan, June 7, 1961.,

6/ 19,613 2 Claims. (Cl. 323-89) This invention relates to a current regulator wherein a magnetic operational amplifier of, for example, the voltage-feedback type, is used to supply to a load a current proportional to the input voltage.

It is an object of the present invention to provide a new current regulator as stated above which has high reliability.

The nature and details of the invention and the manner in which the fore-going object, as well as other objects and advantages as will presently become apparent, may best be achieved will be understood by reference to the following description of a representative embodiment of the invention taken in conjunction with the accompanying drawing in which like parts are designated by like reference characters, and in which:

FIG. 1 is an electrical connection diagram showing the composition of a magnetic operational amplifier of voltage-feedback type; and

FIG. 2 is an electrical circuit diagram of one embodiment of the current regulator according to the present invention.

In general, a magnetic operational amplifier of the voltage-feedback type is composed, as is indicated in FIG. 1, of an input resistance Z, connected to a parallel connection of a magnetic amplifier MA and a feedback resistance Z which feeds back output voltage to the input terminal. It is known that the following relation between the input voltage 2, and. the output voltage 12 of this operational amplifier is valid.

Such a magnetic operational amplifier of voltagefeedback type as the foregoing is used in the current regulator of the present invention to supply to a load a current which is proportional to the input voltage.

The embodiment of the present invention shown in FIG. 2 has a magnetic amplifier MA having an input control terminal 1 which has negative feedback to the input, an input control terminal 2 which has positive feedback, and an output terminal 3. When inputs of the same polarity are impressed on these input terminals 1 and 2, the input of the terminal 2 imparts a subtraction effect with respect to the input of the terminal 1, and the differential signal of the two input signals is amplified and appears as magnitude of voltage at the output terminal 3.

In such a magnetic amplifier MA having an input terminal 1 and another input terminal 2, windings are provided, for example, two control windings 4 and 5 which are mutually wound so as to energize the same magnetic path. At the same time, the winding directions are so determined that, when voltages of the same polarity are impressed on two input terminals 1 and 2 positioned, respectively, at parts of the control windings 4 and 5, the magnetic fluxes created in the control windings 4 and 5 have mutually opposite directions. That is, the substraction of the two inputs is effected through the states of the magnetic fluxes, and a volage corresponding to the differential signal thereof is produced at the output terminal 3.

In the circuit shown in FIG. 2, a feedback resistance 3,225,292 Patented Dec. 21, 1965 "ice R is connected between the input terminal 1 and output terminal 3 of the magnetic amplifier MA, described above; a resistance R and another feedback resistance R in series connection, are connected between the input terminal 2 and the output terminal 3 of the amplifier MA and a load resistance R is connected between the series junction 6 of the said resistance R and R and the ground. An input voltage e, is impressed on the input terminal 1 by way of an input resistance R Feedback resistance R is used for negatively feeding back the output voltage 2,, into the first input terminal 1 and feedback resistance R serves for positively feeding back the voltage 6 of junction 6 into the second input terminal 2. The resistance R is used for determining the voltage current conversion coefficient, and the voltage difference (c -e at both terminals of the resistance R is fed back into the input side.

In the case of this circuit, if the resistance value of each of the resistance R and R is made to be R and the resistance value of the resistance R to be R,, the following relationships will be valid.

Where:

e is the output voltage of MA e is the voltage at junction 6;

I is the current through R and I is the current through R From the above relationships, the following expression is obtained.

If, now, R and R are so selected that R R the following relationship will be valid.

i IL- R That is, a load current I which is proportional to the input voltage 2, flows through the load R independently of the magnitude of the load. The aforesaid relationship is valid even when the signs of 2 and e are exchanged; that is, the input terminals 1 and 2 are validly exchangeable.

In the above description, the following relations are adopted: R,:R ..R :R :R However, even when the relationship of R =R :R is adopted, the object of this invention can be attained.

The above-described magnetic amplifier is provided with two control windings in order to lead out input terminals. In some cases, however, one control winding and a polarity changer can be used. That is, by adapting the input terminal of the said polarity changer to be the input terminal 2, and connecting its output terminal to an input terminal 1 led out from the said single control winding so as to accomplish subtraction, it

is possible to amplify the differential signal of two input signals in asimilar manner, andthe above Equation 5 is valid.

Furthermore, by arranging the aforesaid magnetic amplifier so-that its output current can flow in both directions, current regulation operation with high sensitivity can be attained also for the case wherein the input is in the vicinity of zero, which is an advantageous feature. The said output currentcan be easily caused to flow-in both directions by using a magnetic amplifier of pushpull type or by adding a suitable bias circuit to the output terminal.

Since, in the voltage-current regulation according to this invention,-a magnetic amplifier can be used, higher reliability than in the-case of an electronic tube type can beattained. Accordingly, the current regulator of this invention can be eifectively used in such apparatuses as control computers. For example, in a loss-rate computer used in such apparatuses as an economic load dispatcher, a circuit for obtaining, with respect to a voltage input, a constant-current output proportional thereto is required For the said circuit, the voltage-current converter of the present invention as'described above can be used as a constant-current circuit.

Although in the foregoing disclosure, the case wherein a magnetic amplifier is used as an amplifier having positive and negative input terminals has been described, other forms of amplifiers can be used in the composition of the circuit of the invention. For example, a magneticmodulator-type amplifier provided with a magnetic modulator and a demodulator can be used. In this case, positive and negative input terminals may be brought out from two control windings which are wound in differential form, similarly as in the case of the magnetic amplifier of the present invention as described hereinbefore. It will be obvious that other amplifiers of general types can also be used in connection with the present invention.

Although this invention has been described with respect to a particular embodiment thereof, it is not to be so limited as changes and modifications may be made therein which are within the full intended scope of the invention, as defined by the appended claims.

What is claimed is:

1. A current regulator which comprises an amplifier having a first and a second control input terminal and an output terminal; said amplifier generating a control voltage corresponding to the difference between the input voltages having the same polarity and applied on said input terminals; a negative feedbackresistance connected between said output terminal and said first input terminal; a resistance adapted to determine the conversion coefficient; a load resistance; a positive feedback resistance connected to said second input terminal and said output terminal; and an input resistance connected to said first input terminal; said resistance for determining the conversion coefl'icient being disposed between said output terminal and said load resistance; and said load resistance being disposed at a junction of said resistance for determining the conversion coeflicient and said positive feedback resistance; said negative and positive feedback resistances being equal to each other so that a current proportional to the input voltage applied on said input resistance is caused to flow through said load.

2. The regulator as defined in claim 1, wherein said amplifier is a magnetic amplifier comprising at least two control windings connected to said negative and positive feedback resistances, respectively, and adapted to excite the same magnetic path and to generate a control voltage corresponding to the dilference between the input voltages having the same polarity applied to the input terminals of said control windings.

References Cited by theExaminer MILTON O. HIRSHFIELD, Primary Examiner.

LLOYD McCOLLUM, ROBERT C. SIMS, Examiners. 

1. A CURRENT REGULATOR WHICH COMPRISES AN AMPLIFIER HAVING A FIRST AND A SECOND CONTROL INPUT TERMINAL AND AN OUTPUT TERMINAL; SAID AMPLIFIER GENERATING A CONTROL VOLTAGE CORRESPONDING TO THE DIFFERENCE BETWEEN THE INPUT VOLTAGES HAVING THE SAME POLARITY AND APPLIED ON SAID INPUT TERMINALS; A NEGATIVE FEEDBACK RESISTANCE CONNECTED BETWEEN SAID OUTPUT TERMINAL AND SAID FIRST INPUT TERMINAL; A RESISTANCE ADAPTED TO DETERMINE THE CONVERSION COEFFICIENT; A LOAD RESISTANCE; A POSITIVE FEEDBACK RESISTANCE CONNECTED TO SAID SECOND INPUT TERMINAL AND SAID OUTPUT TERMINAL; AND AN INPUT RESISTANCE CONNECTED TO SAID FIRST INPUT TERMINAL; SAID RESISTANCE FOR DETERMINING THE CONVERSION COEFFICIENT BEING DISPOSED BETWEEN SAID OUTPUT TERMINAL AND SAID LOAD RESISTANCE; AND SAID LOAD RESISTANCE BEING DISPOSED AT A JUNCTION OF SAID RESISTANCE FOR DETERMINING THE CONVERSION COEFFICIENT AND SAID POSITIVE FEEDBACK RESISTANCE; SAID NEGATIVE AND POSITIVE FEEDBACK RESISTANCES BEING EQUAL TO EACH OTHER SO THAT A CURRENT PROPORTIONAL TO THE INPUT VOLTAGE APPLIED ON SAID INPUT RESISTANCE IS CAUSED TO FLOW THROUGH SAID LOAD. 